Radiative Leptonic Bc→γℓνˉB_c\to \gamma \ell\bar\nu Decay in Effective Field Theory beyond Leading Order

We study the radiative leptonic $B_c\to \gamma\ell\bar\nu$ decays in the nonrelativistic QCD effective field theory, and consider a fast-moving photon. As a result the interactions with the heavy quarks can be integrated out, and thus we arrive at a factorization formula for the decay amplitude. We calculate not only the relevant short-distance coefficients at leading order and next-to-leading order in $\alpha_s$, but also the nonrelativistic corrections at the order $|\bold{v}|^2$ in our analysis. We find out that the QCD corrections can sizably decrease the branching ratio and thus is of great importance in extracting the long-distance operator matrix elements of $B_c$. For the phenomenological application, we present our results for the photon energy, lepton energy and lepton-neutrino invariant mass distribution.Comment: 24 pages, 5 figures, and 2 tables;new references and a new table added and typos correcte

Estimation of Semileptonic Decays of BcB_c Meson to S-wave Charmonia with NRQCD

We study the semileptonic differential decay rates of $B_c$ meson to S-wave charmonia, $\eta_c$ and $J/\Psi$, at the next-to-leading order accuracy in the framework of NRQCD. In the heavy quark limit, $m_b \to \infty$, we obtain analytically the asymptotic expression for the ratio of NLO form factor to LO form factor. Numerical results show that the convergence of the ratio is perfect. At the maximum recoil region, we analyze the differential decay rates in detail with various input parameters and polarizations of $J/\psi$, which can now be checked in the LHCb experiment. Phenomenologically, the form factors are extrapolated to the minimal recoil region, and then the $B_c$ to charmonium semileptonic decay rates are estimated.Comment: 9 pages, 2 figure and 4 table

Hidden-charm molecular pentaquarks and their charm-strange partners

In the framework of one-pion-exchange (OPE) model, we study the hidden-charm and charm-strange molecular pentaquark systems composed of a heavy baryon $(\Sigma_c, \Sigma_c^*)$ and a vector meson $(\bar{K}^*, \bar{D}^*)$, where the S-D mixing effect is considered in our calculation. Our result shows that the $\Sigma_c\bar{D}^*$ molecular state with $(I=1/2,J^P=3/2^-)$ and the $\Sigma_c^*\bar{D}^*$ molecular state with $(I=1/2,J^P=5/2^-)$ exist in the mass range of the observed $P_c(4380)$ and $P_c(4450)$, respectively. Moreover, we predict two other hidden-charm molecular pentaquarks with configurations $\Sigma_c\bar{D}^*$ $(I=3/2, J^P=1/2^-)$ and $\Sigma_c^*\bar{D}^*$ $(I=3/2, J^P=1/2^-)$ and two charm-strange molecular pentaquarks $P_{cs}(3340)$ and $P_{cs}(3400)$ corresponding to the $\Sigma_c\bar{K}^*$ configuration with $(I=1/2, J^P=3/2^-)$ and the $\Sigma_c^*\bar{K}^*$ configuration with $(I=1/2, J^P=5/2^-)$, respectively. Additionally, we also predict some hidden-bottom $\Sigma_b^{(*)}B^*$ and $B_c$-like $\Sigma_c^{(*)}B^*/\Sigma_b^{(*)}\bar{D}^*$ pentaquarks.Comment: Invited paper for NPA special issue on Recent Progress in Strangeness and Charm Nuclear Physics. 23 pages, 3 figures and 7 tables. The version accepted by NP